Abstract

The aim was to assess the treatment efficiencies of experimental storm water detention (extended
storage) systems based on the Atlantis Water Management Limited detention cells receiving concentrated
runoff that has been primary treated by filtration with different inert aggregates. Randomly collected gully
pot liquor was used in stead of road runoff. To test for a 'worst case scenario', the experimental system
received higher volumes and pollutant concentrations in comparison to real detention systems under real
(frequently longer but diluted) runoff events. Gravel (6 and 20 mm), sand (1.5 mm), Ecosoil (inert 2 mm
aggregate provided by Atlantis Water Management Limited), block paving and turf were tested in terms of
their influence on the water quality. Concentrations of five-day @ 20� C ATU biochemical oxygen demand
(BOD) in contrast to suspended solids (SS) were frequently reduced to below international secondary
wastewater treatment standards. The denitrification process was not completed. This resulted in higher
outflow than inflow nitrate-nitrogen concentrations. An analysis of variance indicated that some systems
were similar in terms of most of their treatment performance variables including BOD and SS. It follows that
there is no advantage in using additional aggregates with high adsorption capacities in the primary treatment
stage.